/*
 *  Vector2.h
 *  RTDemo
 *
 *  Created by steveca  on 10/05/09.
 *  Copyright 2009 __MyCompanyName__. All rights reserved.
 *
 */

#ifndef __VECTOR2_H__
#define __VECTOR2_H__

namespace RTRT
{
    class Vector2
    {
    public:
        float x, y;
        
    public:
        inline Vector2()
        {
        }
        
        inline Vector2(const float fX, const float fY )
        : x( fX ), y( fY )
        {
        }
        
        inline explicit Vector2( const float scaler )
        : x( scaler), y( scaler )
        {
        }
        
        inline explicit Vector2( const float afCoordinate[2] )
        : x( afCoordinate[0] ),
        y( afCoordinate[1] )
        {
        }
        
        inline explicit Vector2( const int afCoordinate[2] )
        {
            x = (float)afCoordinate[0];
            y = (float)afCoordinate[1];
        }
        
        inline explicit Vector2( float* const r )
        : x( r[0] ), y( r[1] )
        {
        }
        
		inline float operator [] ( const size_t i ) const
        {
            assert( i < 2 );
            
            return *(&x+i);
        }
        
		inline float& operator [] ( const size_t i )
        {
            assert( i < 2 );
            
            return *(&x+i);
        }
        
		/// Pointer accessor for direct copying
		inline float* ptr()
		{
			return &x;
		}
		/// Pointer accessor for direct copying
		inline const float* ptr() const
		{
			return &x;
		}
        
        /** Assigns the value of the other vector.
         @param
         rkVector The other vector
         */
        inline Vector2& operator = ( const Vector2& rkVector )
        {
            x = rkVector.x;
            y = rkVector.y;
            
            return *this;
        }
        
		inline Vector2& operator = ( const float fScalar)
		{
			x = fScalar;
			y = fScalar;
            
			return *this;
		}
        
        inline bool operator == ( const Vector2& rkVector ) const
        {
            return ( x == rkVector.x && y == rkVector.y );
        }
        
        inline bool operator != ( const Vector2& rkVector ) const
        {
            return ( x != rkVector.x || y != rkVector.y  );
        }
        
        // arithmetic operations
        inline Vector2 operator + ( const Vector2& rkVector ) const
        {
            return Vector2(
                           x + rkVector.x,
                           y + rkVector.y);
        }
        
        inline Vector2 operator - ( const Vector2& rkVector ) const
        {
            return Vector2(
                           x - rkVector.x,
                           y - rkVector.y);
        }
        
        inline Vector2 operator * ( const float fScalar ) const
        {
            return Vector2(
                           x * fScalar,
                           y * fScalar);
        }
        
        inline Vector2 operator * ( const Vector2& rhs) const
        {
            return Vector2(
                           x * rhs.x,
                           y * rhs.y);
        }
        
        inline Vector2 operator / ( const float fScalar ) const
        {
            assert( fScalar != 0.0 );
            
            float fInv = 1.0 / fScalar;
            
            return Vector2(
                           x * fInv,
                           y * fInv);
        }
        
        inline Vector2 operator / ( const Vector2& rhs) const
        {
            return Vector2(
                           x / rhs.x,
                           y / rhs.y);
        }
        
        inline const Vector2& operator + () const
        {
            return *this;
        }
        
        inline Vector2 operator - () const
        {
            return Vector2(-x, -y);
        }
        
        // overloaded operators to help Vector2
        inline friend Vector2 operator * ( const float fScalar, const Vector2& rkVector )
        {
            return Vector2(
                           fScalar * rkVector.x,
                           fScalar * rkVector.y);
        }
        
        inline friend Vector2 operator / ( const float fScalar, const Vector2& rkVector )
        {
            return Vector2(
                           fScalar / rkVector.x,
                           fScalar / rkVector.y);
        }
        
        inline friend Vector2 operator + (const Vector2& lhs, const float rhs)
        {
            return Vector2(
                           lhs.x + rhs,
                           lhs.y + rhs);
        }
        
        inline friend Vector2 operator + (const float lhs, const Vector2& rhs)
        {
            return Vector2(
                           lhs + rhs.x,
                           lhs + rhs.y);
        }
        
        inline friend Vector2 operator - (const Vector2& lhs, const float rhs)
        {
            return Vector2(
                           lhs.x - rhs,
                           lhs.y - rhs);
        }
        
        inline friend Vector2 operator - (const float lhs, const Vector2& rhs)
        {
            return Vector2(
                           lhs - rhs.x,
                           lhs - rhs.y);
        }
        // arithmetic updates
        inline Vector2& operator += ( const Vector2& rkVector )
        {
            x += rkVector.x;
            y += rkVector.y;
            
            return *this;
        }
        
        inline Vector2& operator += ( const float fScaler )
        {
            x += fScaler;
            y += fScaler;
            
            return *this;
        }
        
        inline Vector2& operator -= ( const Vector2& rkVector )
        {
            x -= rkVector.x;
            y -= rkVector.y;
            
            return *this;
        }
        
        inline Vector2& operator -= ( const float fScaler )
        {
            x -= fScaler;
            y -= fScaler;
            
            return *this;
        }
        
        inline Vector2& operator *= ( const float fScalar )
        {
            x *= fScalar;
            y *= fScalar;
            
            return *this;
        }
        
        inline Vector2& operator *= ( const Vector2& rkVector )
        {
            x *= rkVector.x;
            y *= rkVector.y;
            
            return *this;
        }
        
        inline Vector2& operator /= ( const float fScalar )
        {
            assert( fScalar != 0.0 );
            
            float fInv = 1.0 / fScalar;
            
            x *= fInv;
            y *= fInv;
            
            return *this;
        }
        
        inline Vector2& operator /= ( const Vector2& rkVector )
        {
            x /= rkVector.x;
            y /= rkVector.y;
            
            return *this;
        }
        
        /** Returns the length (magnitude) of the vector.
         @warning
         This operation requires a square root and is expensive in
         terms of CPU operations. If you don't need to know the exact
         length (e.g. for just comparing lengths) use squaredLength()
         instead.
         */
        inline float length () const
        {
            return Math::sqrt( x * x + y * y );
        }
        
        /** Returns the square of the length(magnitude) of the vector.
         @remarks
         This  method is for efficiency - calculating the actual
         length of a vector requires a square root, which is expensive
         in terms of the operations required. This method returns the
         square of the length of the vector, i.e. the same as the
         length but before the square root is taken. Use this if you
         want to find the longest / shortest vector without incurring
         the square root.
         */
        inline float squaredLength () const
        {
            return x * x + y * y;
        }
        
        /** Calculates the dot (scalar) product of this vector with another.
         @remarks
         The dot product can be used to calculate the angle between 2
         vectors. If both are unit vectors, the dot product is the
         cosine of the angle; otherwise the dot product must be
         divided by the product of the lengths of both vectors to get
         the cosine of the angle. This result can further be used to
         calculate the distance of a point from a plane.
         @param
         vec Vector with which to calculate the dot product (together
         with this one).
         @returns
         A float representing the dot product value.
         */
        inline float dotProduct(const Vector2& vec) const
        {
            return x * vec.x + y * vec.y;
        }
        
        /** Normalises the vector.
         @remarks
         This method normalises the vector such that it's
         length / magnitude is 1. The result is called a unit vector.
         @note
         This function will not crash for zero-sized vectors, but there
         will be no changes made to their components.
         @returns The previous length of the vector.
         */
        inline float normalise()
        {
            float fLength = Math::sqrt( x * x + y * y);
            
            // Will also work for zero-sized vectors, but will change nothing
            if ( fLength > 1e-08 )
            {
                float fInvLength = 1.0 / fLength;
                x *= fInvLength;
                y *= fInvLength;
            }
            
            return fLength;
        }
        
        
        
        /** Returns a vector at a point half way between this and the passed
         in vector.
         */
        inline Vector2 midPoint( const Vector2& vec ) const
        {
            return Vector2(
                           ( x + vec.x ) * 0.5,
                           ( y + vec.y ) * 0.5 );
        }
        
        /** Returns true if the vector's scalar components are all greater
         that the ones of the vector it is compared against.
         */
        inline bool operator < ( const Vector2& rhs ) const
        {
            if( x < rhs.x && y < rhs.y )
                return true;
            return false;
        }
        
        /** Returns true if the vector's scalar components are all smaller
         that the ones of the vector it is compared against.
         */
        inline bool operator > ( const Vector2& rhs ) const
        {
            if( x > rhs.x && y > rhs.y )
                return true;
            return false;
        }
        
        /** Sets this vector's components to the minimum of its own and the
         ones of the passed in vector.
         @remarks
         'Minimum' in this case means the combination of the lowest
         value of x, y and z from both vectors. Lowest is taken just
         numerically, not magnitude, so -1 < 0.
         */
        inline void makeFloor( const Vector2& cmp )
        {
            if( cmp.x < x ) x = cmp.x;
            if( cmp.y < y ) y = cmp.y;
        }
        
        /** Sets this vector's components to the maximum of its own and the
         ones of the passed in vector.
         @remarks
         'Maximum' in this case means the combination of the highest
         value of x, y and z from both vectors. Highest is taken just
         numerically, not magnitude, so 1 > -3.
         */
        inline void makeCeil( const Vector2& cmp )
        {
            if( cmp.x > x ) x = cmp.x;
            if( cmp.y > y ) y = cmp.y;
        }
        
        /** Generates a vector perpendicular to this vector (eg an 'up' vector).
         @remarks
         This method will return a vector which is perpendicular to this
         vector. There are an infinite number of possibilities but this
         method will guarantee to generate one of them. If you need more
         control you should use the Quaternion class.
         */
        inline Vector2 perpendicular(void) const
        {
            return Vector2 (-y, x);
        }
        /** Calculates the 2 dimensional cross-product of 2 vectors, which results
         in a single floating point value which is 2 times the area of the triangle.
         */
        inline float crossProduct( const Vector2& rkVector ) const
        {
            return x * rkVector.y - y * rkVector.x;
        }
        /** Generates a new random vector which deviates from this vector by a
         given angle in a random direction.
         @remarks
         This method assumes that the random number generator has already
         been seeded appropriately.
         @param
         angle The angle at which to deviate in radians
         @param
         up Any vector perpendicular to this one (which could generated
         by cross-product of this vector and any other non-colinear
         vector). If you choose not to provide this the function will
         derive one on it's own, however if you provide one yourself the
         function will be faster (this allows you to reuse up vectors if
         you call this method more than once)
         @returns
         A random vector which deviates from this vector by angle. This
         vector will not be normalised, normalise it if you wish
         afterwards.
         */
        /*
        inline Vector2 randomDeviant(
                                     float angle) const
        {
            
            angle *=  Math::UnitRandom() * Math::TWO_PI;
            float cosa = cos(angle);
            float sina = sin(angle);
            return  Vector2(cosa * x - sina * y,
                            sina * x + cosa * y);
        }
        */
        /** Returns true if this vector is zero length. */
        inline bool isZeroLength(void) const
        {
            float sqlen = (x * x) + (y * y);
            return (sqlen < (1e-06 * 1e-06));
            
        }
        
        /** As normalise, except that this vector is unaffected and the
         normalised vector is returned as a copy. */
        inline Vector2 normalisedCopy(void) const
        {
            Vector2 ret = *this;
            ret.normalise();
            return ret;
        }
        
        /** Calculates a reflection vector to the plane with the given normal .
         @remarks NB assumes 'this' is pointing AWAY FROM the plane, invert if it is not.
         */
        inline Vector2 reflect(const Vector2& normal) const
        {
            return Vector2( *this - ( 2 * this->dotProduct(normal) * normal ) );
        }
        
        // special points
        static const Vector2 ZERO;
        static const Vector2 UNIT_X;
        static const Vector2 UNIT_Y;
        static const Vector2 NEGATIVE_UNIT_X;
        static const Vector2 NEGATIVE_UNIT_Y;
        static const Vector2 UNIT_SCALE;
        
        /** Function for writing to a stream.
         */
        inline friend std::ostream& operator <<
        ( std::ostream& o, const Vector2& v )
        {
            o << "Vector2(" << v.x << ", " << v.y <<  ")";
            return o;
        }
        
    };
}



#endif
